It has been over 40 years since the original report by Salmon and Daughaday demon­ strating that the ability of GH to stimulate sulfation of cartilage was mediated by a "sulfation factor. " In the ensuing decades, it has become apparent that this "sulfation factor activity" encompasses a complex system ofligands (IGFs), receptors, and carrier proteins that are, in tum, responsible for a wide array of cellular actions. The IGF system has been demonstrated to be critically involved in both intrauterine and postnatal growth, and to have important implications in cancer biology as well, owing to the ability of the IGFs to function in endocrine, paracrine, and autocrine modes and given the wide distri­ bution of IGFs in virtually every organ system. The contributions to The /GF System reflect the wide span of interest in the IGF system and its implications for normal and abnormal growth and metabolism. The chapters have been divided into four broad sections: I. Molecular biology of the IGF system; II. Bio­ logical actions of the IGFs; III. IGF physiology; and IV. Clinical aspects of the IGFs. We have made every effort to highlight the major contemporary themes in IGF biology, but as is inevitable in such a fast-moving field, perspectives will continue to change as new information is accumulated.

1 Historical Perspective: The Origins and Development of the Somatomedin Hypothesis.- I Molecular Biology of the IGF System.- 2 Molecular Biology of IGF-I and IGF-II.- 3 Regulation of IGF Gene Expression.- 4 Molecular Biology of the Type 1 IGF Receptor.- 5 Molecular Biology of the IGF-II/Mannose-6-Phosphate Receptor.- 6 Molecular Biology of the IGF Binding Proteins.- II Biological Actions of the IGFs.- 7 IGF-I Receptor Function: Transducing the IGF-I Signal into Intracellular Events.- 8 Type 2 IGF Receptor-Mediated Events.- 9 Alternative IGF-Related Receptors.- 10 IGF Binding Proteins as Modulators of IGF Action.- 11 IGF-Independent Actions of the IGF Binding Proteins.- 12 IGF Binding Proteins and Extracellular Matrix.- 13 Biological Actions of Proteolytic Fragments of the IGF Binding Proteins.- 14 The IGF Binding Protein Superfamily.- 15 IGFs and Cell Growth.- 16 Posttranslational Modification of the IGF Binding Proteins.- III IGF Physiology.- 17 IGFs in the Female Reproductive System.- 18 The IGF Axis in the Male Reproductive System.- 19 IGFs and the Nervous System.- 20 IGF System Components and Their Role in Bone Metabolism.- 21 IGFs and Skeletal Muscle.- 22 IGFs and the Digestive Tract.- 23 Actions of IGF System Proteins from Studies of Transgenic and Gene Knockout Models.- IV Clinical Aspects of the IGFs.- 24 Metabolic Effects of IGFs.- 25 Clinical Uses of IGF-I and IGF Binding Protein Assays.- 26 IGF Binding Protein Proteolysis in Various Clinical States.- 27 IGF Deficiency.- 28 Tumor Hypoglycemia Linked to IGF-II.- 29 IGFs in the Evaluation of Acromegaly.- 30 IGF in the Treatment of Diabetes.- 31 IGF-I Treatment of Growth Hormone Insensitivity.